The present invention relates generally to an inter-connector formation method. Specifically, the present invention relates to an inter-connector formation technique for forming an inter-connector for interconnecting two electronic components.
Inter-connectors are typically used for interconnecting electronic components, for example, devices on circuit boards or circuits on integrated circuit chips. The inter-connectors may be further used for interconnecting an integrated circuit chip and a device.
Interconnections between electronic components are generally classified into at least two broad categories of xe2x80x9crelatively permanentxe2x80x9d and xe2x80x9creadily demountablexe2x80x9d. An example of a xe2x80x9crelatively permanentxe2x80x9d connector is, for example, a wire bond. The use of a wire bond for interconnecting two electronic components requires a contact element or xe2x80x9cwirexe2x80x9d element to be bonded on both the electronic components. An xe2x80x9cunbonding processxe2x80x9d must be used to separate the electronic components.
An example of a xe2x80x9creadily demountablexe2x80x9d connector is a rigid contact structure of one electronic component for insertion into a resilient socket of another electronic component. Another example of a xe2x80x9creadily demountablexe2x80x9d connector is spring-like contact structure of one electronic component for connecting to a terminal of another electronic component.
The spring-like contact structure, also known as an inter-connector, generally requires a certain amount of contact force to effect reliable pressure contact to a terminal of an electronic component. Therefore, the shape and metallurgy of the inter-connector are important factors in determining the effectiveness of the inter-connector for making pressure connection to the terminal of the electronic component.
U.S. Pat. No. 6,268,015 by Mathieu describes a method for making such an inter-connector. In Mathieu, lithographic and planarisation methods were used to xe2x80x9cmakexe2x80x9d the inter-connectors in segments. The different segments of the inter-connector in Mathieu were sequentially xe2x80x9cstackedxe2x80x9d by deposition of a conductive material in a piece-meal manner. Therefore, the inter-connector in Mathieu is formed from discontinued segments having joints therebetween. Metallurgically, the joint stress due to joining a pair of inter-connector segments and stress concentration at the joints due forces applied to the inter-connector can lead to the mechanical failure of the inter-connector in Mathieu.
Another disclosed invention describes the use of a cavity to make an inter-connector formed from a single physically continuous segment of conductive material. The cavity described therein is a concavity having an opening. The cavity inwardly converges towards the base of the cavity. The conductive material is deposited into the opening for partially filling the cavity in a single step to form the inter-connector. However, the dimension and cross-sectional thickness formed using the disclosed method cannot be accurately or consistently controlled.
Hence, this clearly affirms a need for an inter-connector formation method for addressing the foregoing disadvantages of conventional methods for making inter-connectors.
In accordance with a first aspect of the invention, there is disclosed an inter-connector formation method for forming a wafer-level inter-connector for use as an electro-mechanical inter-connector, the inter-connector formation method comprising the steps of:
forming a first passage in a first sacrificial layer of a first sacrificial material, the first sacrificial layer being formed over a portion of a substrate, the first passage extending from a signal terminal to an opening in the first sacrificial layer, and the signal terminal being formed on the substrate;
forming a protrusion over the opening in the first sacrificial layer, the protrusion being of a second sacrificial material and the second sacrificial material further extending from the protrusion to the signal terminal;
forming a second passage in a second sacrificial layer of the first sacrificial material, the second sacrificial layer being formed over a portion of the first sacrificial layer and the protrusion, the second passage extending from the protrusion to an opening in the second sacrificial layer;
removing the second sacrificial material to thereby remove the protrusion and to expose a structure channel extending from the signal terminal to the opening in the second sacrificial layer, and the structure channel defining the shape and dimension of the inter-connector; and
depositing a structure material into the opening of the second sacrificial layer and thereby filling the structure channel therewith, the structure material taking the shape and dimension of the structure channel to form the inter-connector extending from the signal terminal to the opening in the second sacrificial layer.
In accordance with a second aspect of the invention, there is disclosed an inter-connector formation system for forming an inter-connector for use as an electro-mechanical connector, the inter-connector formation system comprising:
means for forming a first passage in a first sacrificial layer of a first sacrificial material, the first sacrificial layer being formed over a portion of a substrate, the first passage extending from a signal terminal to an opening in the first sacrificial layer, and the signal terminal being formed on the substrate;
means for forming a protrusion over the opening in the first sacrificial layer, the protrusion being of a second sacrificial material and the second sacrificial material further extending from the protrusion to the signal terminal;
means for forming a second passage in a second sacrificial layer of the first sacrificial material, the second sacrificial layer being formed over a portion of the first sacrificial layer and the protrusion, the second passage extending from the protrusion to an opening in the second sacrificial layer;
means for removing the second sacrificial material to thereby remove the protrusion and to expose a structure channel extending from the signal terminal to the opening in the second sacrificial layer, and the structure channel defining the shape and dimension of the inter-connector; and
means for depositing a structure material into the opening of the second sacrificial layer and thereby filling the structure channel therewith, the structure material taking the shape and dimension of the structure channel to form the inter-connector extending from the signal terminal to the opening in the second sacrificial layer.
In accordance with a third aspect of the invention, there is disclosed an inter-connector formation method for forming an inter-connector for use as an electro-mechanical connector, the inter-connector formation method comprising the steps of:
forming a structure channel in a sacrificial layer of a sacrificial material, the sacrificial layer being formed over a portion of a substrate, the structure channel extending from a signal terminal to an opening in the sacrificial layer, and the signal terminal being formed on the substrate, and the structure channel defining the shape and dimension of the inter-connector; and
depositing a structure material into the opening of the sacrificial layer and thereby filling the structure channel therewith, the structure material taking the shape and dimension of the structure channel to form the inter-connector extending from the signal terminal to the opening in the sacrificial layer,
wherein the inter-connector comprises of at least a first elongated portion and a second elongated portion, one end of the first elongated portion being coincident with one end of the second elongated portion and the first elongated portion of the inter-connector being perpendicular to the second elongated portion of the inter-connector.